1. Field of the Invention
The present invention relates generally to a Broadband Wireless Access (BWA) system. More particularly, the present invention relates to an apparatus and a method for circuit mode resource allocation.
2. Description of the Related Art
A Broadband Wireless Access (BWA) system based on an Orthogonal Frequency Division Multiplexing (OFDM) allocates resources to a user for transmission and reception of DownLink (DL) packets and UpLink (UL) packets, and informs the user of the resource allocation using a resource allocation message (DL/UL-MAP Information Element (IE) of Institute of Electrical and Electronics Engineers (IEEE) 802.16e. In a service which periodically transmits packets, e.g., Voice over Internet Protocol (VoIP) service, when a base station allocates the resources constantly using the resource allocation message, it may cause unnecessary resource waste. To avoid this problem, by using a circuit mode, the base station can allocate a fixed radio resource of a frame for a mobile station having the service of the periodic traffic. Herein, contrary to the circuit mode, a packet mode allocates resources constantly using the resource allocation message. Even without a separate resource allocation message, the mobile station allocated the radio resource in the circuit mode that can fixedly occupy the resource until the radio resource is changed or the allocated radio resource is released. Since the resource allocation message is not needed in every frame, overhead due to the resource allocation message can be reduced.
Meanwhile, the conventional circuit mode resource allocation has two shortcomings.
First, the Downlink (DL) of the IEEE 802.16e adopts a two-dimensional (2D) allocation scheme, whereas the circuit mode uses a one-dimensional (1D) allocation scheme, which does not ensure backward compatibility with existing standards.
Second, since the circuit mode resource allocation is not continuous and is subject to holes, the entire radio resource may not be efficiently utilized. For instance, in the resource allocation, when a hole generated from the circuit mode resource deallocation is less than a region required for the resource allocation, it is impossible to allocate the resource in the hole. While the hole can be allocated in the packet mode, packets need to be divided when the hole is less than the required region, which requires an additional resource allocation message. As such, the conventional method cannot achieve the efficient resource allocation in the circuit mode resource allocation and deallocation.